doc/manuals: support OSMO_GSM_MANUALS_DIR

Instead of only relying on pkg-config, support the environment variable
and fallback path like in other Osmocom repositories too. The same
script is used in other Osmocom repositories where manuals are built
without autotools.

Related: OS#4912
Change-Id: Iecfbfc2a7588c316642aa37be637cf3c02f76ac4

doc/manuals/Makefile

@@ -1,4 +1,4 @@
-OSMO_GSM_MANUALS_DIR:=$(shell pkg-config osmo-gsm-manuals --variable=osmogsmmanualsdir)
+OSMO_GSM_MANUALS_DIR:=$(shell ./osmo-gsm-manuals-dir.sh)
 
 sdcdir = .
 

doc/manuals/osmo-gsm-manuals-dir.sh

@@ -0,0 +1,26 @@
+#!/bin/sh -e
+# Find OSMO_GSM_MANUALS_DIR and print it to stdout. Print where it was taken from to stderr.
+
+# Find it in env, pkg-conf and ../../../osmo-gsm-manuals
+RET="$OSMO_GSM_MANUALS_DIR"
+if [ -n "$RET" ]; then
+	RET="$(realpath $RET)"
+	echo "OSMO_GSM_MANUALS_DIR: $RET (from env)" >&2
+else
+	RET="$(pkg-config osmo-gsm-manuals --variable=osmogsmmanualsdir 2>/dev/null || true)"
+	if [ -n "$RET" ]; then
+		echo "OSMO_GSM_MANUALS_DIR: $RET (from pkg-conf)" >&2
+	else
+		RET="$(realpath $(realpath $(dirname $0))/../../../osmo-gsm-manuals)"
+		echo "OSMO_GSM_MANUALS_DIR: $RET (fallback)" >&2
+	fi
+fi
+
+# Print the result or error message
+if [ -d "$RET" ]; then
+	echo "$RET"
+else
+	echo "ERROR: OSMO_GSM_MANUALS_DIR does not exist!" >&2
+	echo "Install osmo-gsm-manuals or set OSMO_GSM_MANUALS_DIR." >&2
+	exit 1
+fi